A sensitive trimethylamine-N-oxide aldolase assay in two steps without deproteinisation

A two-step assay for trimethylamine-N-oxide aldolase (the target enzyme) is described in which the second step, the indicator reaction, is of the enzy matic end-point type. This indicator reaction is carried out at a slightly alkaline pH, outside the target enzyme's active pH range. An effective inac tivation of the target enzyme is thus obtained solely by shifting the pH to that of the indicator reaction, thereby avoiding a deproteinisation step. By inserting a downward pH step as the stopping method, many samples may be collected and applied to the indicator reaction simultaneously. These feat ures make the method very productive and easy to perform. (C) 2000 Society of Chemical Industry.